1. Field of the Invention
The invention concerns electromagnetic delivery systems for use of photodynamic therapy in topical applications.
2. Information Disclosure Statement
Photodynamic Therapy is a relatively new use for electromagnetic radiation in fighting disease. Photodynamic therapy involves the use of light to activate certain pharmaceuticals, known as photosensitizing agents, that are generally injected into the body. Exposure to electromagnetic radiation activates the molecules in these drugs, inducing them to kill cancerous cells in the body.
This promising technique is especially useful because it is relatively non-invasive, quick, and is accomplished with reduced side-effects associated with other cancer treatments such as chemotherapy. It can also work to kill cancer cells without causing significant damage to healthy tissue in the body.
The first step in photodynamic therapy is to introduce cancer-killing photosensitizing agents into the body, either orally or by injection. The agents are absorbed in cells throughout the body, but remain in cancerous cells. After a period of time, the agents remain primarily in cancerous cells, and can then be irradiated. Laser light is then applied to the areas containing cancerous cells, which activates the drugs in the tumors and kills those cells.
Because most therapeutic laser light cannot penetrate farther than a few centimeters into the body through the skin, photodynamic therapy is most often used to treat skin cancer or destroy tumors close to the skin. It is also available to treat lung cancer or esophageal cancer, where tumors are sufficiently close to oral passages so light can reach them when a fiber is inserted down the patient's airway.
For topical applications, a large portion of light aimed at the treatment area is reflected off the skin. This raises concerns as to efficiency and speed of the procedure, as well as to the safety of such procedures. Exposure to radiation used in some photodynamic therapy procedures is a concern for the patient and possibly the operator. Patients have suffered injury, especially eye injury, from exposure to laser radiation during surgical procedures. It is useful to be able to protect other areas of the body while irradiating target areas.
The prior art discloses methods for increased efficiency of radiation delivery and safety. Policastro discloses, in U.S. Pat. No. 5,309,925, a modified metallic foil used as a protective barrier in laser surgery. The foil surface is modified so as to diffuse the laser light into multiple beams to dissipate the energy of the reflected laser light. It addresses safety concerns and is offered as a method to protect patients and surgical staff from damage due to reflected laser beams. This invention is utilized as a barrier placed on the patient in areas adjacent to the treatment to protect the patient.
U.S. Pat. No. 6,231,593, by Meserol, discloses a device for using hydrogel as a means of coupling radiation to the skin in photodynamic therapy. This invention consists of a cover that houses a fiber-optic array and hydrogel for use in coupling electromagnetic energy and photopharmaceuticals. The hydrogel is also useful for softening and hydrating the stratum corneum to facilitate transmission of light and photopharmaceuticals. This invention is useful for topical treatment of dermal lesions. However, this invention is meant to be used as a patch, or a stationary cover designed to treat a specific lesion on the skin over a period of time. It is not practical for scanning over a large lesion, and may be cumbersome for treating areas of the body that are oddly shaped or otherwise not conducive to a patch.
Thus, there is a need for a protective photodynamic therapy delivery system that is movable over the treatment area, easily conformable to the contours of the treatment area, and coupled with the delivery device so as to avoid the need for separate protective equipment. The present invention fulfills this need, by disclosing a device that is simultaneously a handpiece, laser light delivery system and a protective barrier against irradiation of unintended areas of the patient's body or the medical professionals performing the procedure.